I learned in my Physical Science class radioactive elements give out large amounts of energy. So i thought "Huh. The Chaos Emeralds emit large amounts of energy. They must be radioactive!". With this in mind, i can conclude the reason why Sonic and my other characters change their appearance: High amounts of radioactivity exposure.
Let's look a Sonic. He 1st was exposed the the energy of the Chaos Emeralds in sonic 1, but that was small. In Sonic 2, he actually used it's power to turn Super Sonic. This may have given him extremely large amounts of radiation. The changes to his body where slow. But after continueis use of the chaos emeralds, Sonic's body has lost significant weight (which happens often with radioactive exposures), has sudden body growth, and even a change in eye color (which means the radioactivity has changed Sonic's genetic makeup; so if you compare his genes to one of his relatives, they won't be the same.)! With rapid body growth, comes change in vocal cords, which is why Sonic's voice is always changing.
Tails and knuckles share mostly all of Sonic's traits. I don't understand why knuckles hasn't died of radioactivity, because he literally sits on a a giant radioactive rock.
Shadow has suffered from minor radioactivity; with side-effects such as a deepened voice, and memory lost!
Silver for some reason has been unchanged by the energy of the chaos emeralds or the time stones. Probably because future genes might be more resistant to radioactivity than ours.
The worst who has suffered from the radioactivity is Dr. Eggman. He has handled the Chaos Emeralds, Master Emerald, and Time Stones Multiple times. This has caused sudden and dramatic weight lost and aperence on his face. I worry the doctor might die very fast if he doesn't handle those stones more carefully.
Hopefully, none of our heroes will die of radioactive exposure (or grow body parts in places they don't belong). No wonder Mario looks the same as he did 25 years ago. SilverPlays97!--->Keep moving forward<---! 11:43, January 17, 2013 (UTC)